10.
The measured current at this point is the "start mark", write it down. Be sure to
have the PA Bias set to the lowest possible value.
11.
Now adjust bias so that measure current is 500mA higher than this "start mark".
E.g. you measure 460mA in the previous step, so the target current is around
960mA (460+500).
FAQ PA Bias
Q: I am not able to reach the 500mA increase even at PA Bias value 115. What can I do?
A: Be sure to use none-defective, genuine RD16HHF. If one of the 2 PA misfit is
defective, for obvious reason, it is difficult to achieve the 500mA current increase.
Q: I checked, both MOSFETs are okay. What can I do now?
Some RD16HHF required a higher bias voltage to achieve the desired bias current. A
modification to the bias voltage regulator U18 can help here. A resistor of 3k3 between
pin 1 and 4 increases the bias voltage range by 0.8V. If this is still not sufficient use 2k2,
which provides an increase of 1.2V. If these modifications still not get you into the
500mA, check the PA transistors again and consider replacing them.
TX: RF Power Adjustment
Before this step the PA Bias
must
be set using the previous steps.
It is mandatory to connect a dummy load or properly tuned antenna. You will need a
way to measure the generated RF power. Best is to use an oscilloscope or proper RF
power meter. The power meter of the UHSDR TRX can be used. But since it is not
calibrated initially, it is only a rough estimation tool.
The standard mcHF supports 160m to 10m operation, although 160m transmit into an
antenna without additional LPF between PA and antenna is not recommended. It is
recommended to calibrate all bands from 160m to 10m.
5W Power Adjustments
The mcHF is able to produce more than 5W on most bands. However, best signal quality
is achieved with 5W or less. All power levels below 5W are derived from the 5W settings,
thus it is important to calibrate the 5W setting properly.
1.
Choose mode LSB or USB.
